class Circle:
    def __init__(self,radius):
        self.radius = radius

    def area(self):
        pi = 3.14
        return pi * (self.radius ** 2)

    def circumference(self):
        pi = 3.14
        return 2 * pi * self.radius

circle = Circle(7)
print(f"面积:{circle.area()}")
print(f"周长:{circle.circumference()}")